1. Field of the Invention
The present invention relates to an image processing method, and more particularly to a method of performing brightness feature mixing and hierarchical combination on an original image, so as to obtain a high-dynamic-range image.
2. Related Art
With the rapid development of technologies and improvement of living standard of modern people, digital image devices, for example, digital still cameras, increasingly become indispensable in people's lives. Due to advanced researching and developing techniques, the digital still camera is also developed rapidly and becomes the mainstream of the market.
Taking the digital still camera for example, when a captured image has a high-contrast scene (for example, both the sunny sky and the buildings in the shadow are present in the scene), due to output limits of software and hardware of the digital still camera, most of the scene in the dynamic range is sacrificed, and the dynamic range of the entire scene cannot be reserved completely as its original appearance. That is to say, as shown in FIG. 1A, the high-bright region (for example, the cloud in the sky) and the low-bright region (for example, the buildings in the lower part) of the image are quite dim in the imaged picture, and it is rather difficult to present the two regions in one picture without distortion.
Recently, in the prior art, a conventional method is to change the output tone mapping according to the brightness distribution of the shot scene. However, the effect of this method is quite limited. Besides, the problems of unnatural colors and excessive artifact are also caused. In addition, when the digital still camera continuously shoots several pictures, as the pictures are continuously shot and the time intervals of shooting are quite short, it is impossible to combine several pictures in a tone mapping manner when the pictures are continuously shot for the same scene in the prior art. Therefore, through the conventional method, the picture without artifact cannot be effectively obtained, and the operation of the user becomes more inconvenient.